Image sensor, image capturing apparatus, method of performing phase difference focus detection, and storage medium

ABSTRACT

An image sensor comprises: a plurality of microlenses; and a pixel region including, with respect to each of the plurality of microlenses, a plurality of first sensitivity regions formed at first depth from a light incident surface, a plurality of second sensitivity regions formed at second depth which is deeper than the first depth, and a plurality of connection portions that electrically connect the plurality of first regions and the plurality of second regions in different combinations.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application is a continuation of application Ser. No. 17/351,511,filed Jun. 18, 2021, the entire disclosure of which is herebyincorporated by reference.

BACKGROUND OF THE INVENTION Field of the Invention

The preset invention relates to an image sensor, an image capturingapparatus, method of performing phase difference focus detection, and astorage medium.

Description of the Related Art

As one of the focus detection methods of an image capturing apparatus, aso-called on-imaging plane phase difference method is known in whichpupil division signals are acquired using focus detection pixels formedin an image sensor and focus detection is performed by a phasedifference method using the pupil division signals. As a focus detectionpixel, a configuration in which one microlens and a plurality ofsensitivity regions are formed is known, and the pupil division signalscan be acquired by the plurality of sensitivity regions respectivelyreceiving light that has passed through different pupil regions of animaging optical system.

Japanese Patent Laid-Open No. 2016-111678 discloses an image sensor inwhich a plurality of photoelectric conversion regions are arranged intwo directions and that acquires pupil division signals with two pupildivision directions.

Generally, in the phase difference focus detection, there is a problemthat the accuracy of the focus detection deteriorates when thebrightness pattern of the subject, that is, the direction in which thebrightness changes, is close to the division direction of the pupildivision signals.

If an image sensor is configured in which the pixels described inJapanese Patent Laid-Open No. 2016-111687 are reconfigured so as todivide the pupil division signals in a total of four directions, namely,vertical, horizontal, and two diagonal directions, the characteristicsare different between the pixels having different division directionsand the image signals obtained by adding the pupil division signals foreach pixel will vary.

SUMMARY OF THE INVENTION

The present invention has been made in consideration of the abovesituation, and enables an increase in the number of division directionsof pupil regions while suppressing the variation in sensitivities ofimage signals.

According to the present invention, provided is an image sensorcomprising: a plurality of microlenses; and a pixel region including,with respect to each of the plurality of microlenses, a plurality offirst sensitivity regions formed at first depth from a light incidentsurface, a plurality of second sensitivity regions formed at seconddepth which is deeper than the first depth, and a plurality ofconnection portions that electrically connect the plurality of firstregions and the plurality of second regions in different combinations.

Further, according to the present invention, provided is an imagecapturing apparatus comprising: an image sensor comprising: a pluralityof microlenses; and a pixel region including, with respect to each ofthe plurality of microlenses, a plurality of first sensitivity regionsformed at first depth from a light incident surface, a plurality ofsecond sensitivity regions formed at second depth which is deeper thanthe first depth, and a plurality of connection portions thatelectrically connect the plurality of first regions and the plurality ofsecond regions in different combinations, and a focus detection unitthat obtains pupil division signals corresponding to light fluxespassing through different pupil regions, respectively, from signalsoutput from the pixel region and performs phase difference focusdetection for each of structures formed by connecting the plurality offirst regions and the plurality of second regions by the plurality ofconnection portions in the different combinations based on the pupildivision signals, wherein the focus detection unit is implemented by oneor more processors, circuitry or a combination thereof.

Furthermore, according to the present invention, provided is an imagecapturing apparatus comprising: an image sensor comprising: a pluralityof microlenses; and a pixel region including, with respect to each ofthe plurality of microlenses, a plurality of first sensitivity regionsformed at first depth from a light incident surface, a plurality ofsecond sensitivity regions formed at second depth which is deeper thanthe first depth, and a plurality of connection portions thatelectrically connect the plurality of first regions and the plurality ofsecond regions in different combinations, and a focus detection unitthat obtains pupil division signals which divide pupil region fromsignals output from the pixel region and performs phase difference focusdetection based on the pupil division signals, wherein, at least for apart of the plurality of microlenses, the plurality of first regions andthe plurality of second regions are connected by the plurality ofconnection portions to form either a first structure or a secondstructure, the first structure and the second structure dividing a pupilregion in directions orthogonal to each other and being covered withcolor filters of a first color, and at least for another part of theplurality of microlenses, the plurality of first regions and theplurality of second regions are connected by the plurality of connectionportions to form either a third structure or a fourth structure, thethird structure and the fourth structure dividing the pupil region indirections orthogonal to each other and in different directions from thefirst structure and the second structure and being covered with colorfilters of either a second color or a third color, and the first tofourth structures being arranged so that the color filters are in Bayerarrangement, wherein the focus detection unit generates luminancesignals which divide pupil regions based on the pupil division signalsobtained from the first to fourth structures, and performs the phasedifference focus detection based on the luminance signals, and whereinthe focus detection unit is implemented by one or more processors,circuitry or a combination thereof.

Further, according to the present invention, provided is an imagecapturing apparatus comprising: an image sensor comprising: a pluralityof microlenses; and a pixel region including, with respect to each ofthe plurality of microlenses, a plurality of first sensitivity regionsformed at first depth from a light incident surface, a plurality ofsecond sensitivity regions formed at second depth which is deeper thanthe first depth, and a plurality of connection portions thatelectrically connect the plurality of first regions and the plurality ofsecond regions in different combinations, and a focus detection unitthat obtains pupil division signals which divide pupil region fromsignals output from the pixel region and performs phase difference focusdetection based on the pupil division signals, wherein, at least for apart of the plurality of microlenses, the plurality of first regions andthe plurality of second regions are connected by the plurality ofconnection portions to form either a first structure or a secondstructure, the first structure and the second structure dividing a pupilregion in directions orthogonal to each other and being covered withcolor filters of a first color, at least for another part of theplurality of microlenses, the plurality of first regions and theplurality of second regions are connected by the plurality of connectionportions to form either a third structure or a fourth structure, thethird structure and the fourth structure dividing the pupil region indirections orthogonal to each other and in different directions from thefirst structure and the second structure and being covered with colorfilters of either a second color or a third color, and at least foranother part of the plurality of microlenses, the plurality of firstregions and the plurality of second regions are connected by theplurality of connection portions to form either fifth structure or asixth structure, the fifth structure being the same as the firststructure except for not being covered with a color filter, and thesixth structure being the same as the second structure except for notbeing covered with a color filter, wherein the focus detection unitgenerates luminance signals whose pupils are divided based on the pupildivision signals obtained from the first to sixth structures, andperforms the phase difference focus detection based on the luminancesignals, and wherein the focus detection unit is implemented by one ormore processors, circuitry or a combination thereof.

Further, according to the present invention, provided is a method ofperforming phase difference focus detection by obtaining and using pupildivision signals corresponding to light fluxes passing through differentpupil regions from signals output from an image sensor that comprises aplurality of microlenses and a pixel region including, with respect toeach of the plurality of microlenses, a plurality of first sensitivityregions formed at first depth from a light incident surface, a pluralityof second sensitivity regions formed at second depth which is deeperthan the first depth, and a plurality of connection portions thatelectrically connect the plurality of first regions and the plurality ofsecond regions in different combinations, wherein, at least for a partof the plurality of microlenses, the plurality of first regions and theplurality of second regions are connected by the plurality of connectionportions to form either a first structure or a second structure, thefirst structure and the second structure dividing a pupil region indirections orthogonal to each other and being covered with color filtersof a first color, and at least for another part of the plurality ofmicrolenses, the plurality of first regions and the plurality of secondregions are connected by the plurality of connection portions to formeither a third structure or a fourth structure, the third structure andthe fourth structure dividing the pupil region in directions orthogonalto each other and in different directions from the first structure andthe second structure and being covered with color filters of either asecond color or a third color, and the first to fourth structures beingarranged so that the color filters are in Bayer arrangement, the methodcomprising: generating luminance signals by multiplying the pupildivision signals obtained from the first or second structure by a firstcoefficient, multiplying, among the pupil division signals obtained fromthe third or fourth structure, the pupil division signals correspondingto the color filter of the second color by a second coefficient,multiplying, among the pupil division signals obtained from the third orfourth structure, the pupil division signals corresponding to the colorfilter of the third color by a third coefficient, and adding products;and performing the phase difference focus detection based on theluminance signals, wherein, upon generating the luminance signals, theluminance signals corresponding to light fluxes passing through pupilregions divided in first direction are generated by using the pupildivision signals obtained from the first structures and setting thefirst coefficient larger than the second and third coefficients, theluminance signals corresponding to light fluxes passing through pupilregions divided in second direction are generated by using the pupildivision signals obtained from the second structures and setting thefirst coefficient larger than the second and third coefficients, theluminance signals corresponding to light fluxes passing through pupilregions divided in third direction are generated by using the pupildivision signals obtained from the first structures and setting thefirst coefficient smaller than the second and third coefficients, theluminance signals corresponding to light fluxes passing through pupilregions divided in fourth direction are generated by using the pupildivision signals obtained from the second structures and setting thefirst coefficient smaller than the second and third coefficients,wherein the focus detection is performed for each of the first to fourthdirections, and wherein the first to fourth directions are differentfrom each other.

Further, according to the present invention, provided is a method ofperforming phase difference focus detection by obtaining and using pupildivision signals corresponding to light fluxes passing through differentpupil regions from signals output from an image sensor that comprises aplurality of microlenses and a pixel region including, with respect toeach of the plurality of microlenses, a plurality of first sensitivityregions formed at first depth from a light incident surface, a pluralityof second sensitivity regions formed at second depth which is deeperthan the first depth, and a plurality of connection portions thatelectrically connect the plurality of first regions and the plurality ofsecond regions in different combinations, wherein, at least for a partof the plurality of microlenses, the plurality of first regions and theplurality of second regions are connected by the plurality of connectionportions to form either a first structure or a second structure, thefirst structure and the second structure dividing a pupil region indirections orthogonal to each other and being covered with color filtersof a first color, at least for another part of the plurality ofmicrolenses, the plurality of first regions and the plurality of secondregions are connected by the plurality of connection portions to formeither a third structure or a fourth structure, the third structure andthe fourth structure dividing the pupil region in directions orthogonalto each other and in different directions from the first structure andthe second structure and being covered with color filters of either asecond color or a third color, and at least for another part of theplurality of microlenses, the plurality of first regions and theplurality of second regions are connected by the plurality of connectionportions to form either fifth structure or a sixth structure, the fifthstructure being the same as the first structure except for not beingcovered with a color filter, and the sixth structure being the same asthe second structure except for not being covered with a color filter,the method comprising: generating the luminance signals by multiplyingthe pupil division signals obtained from the first or second structureby a first coefficient, multiplying, among the pupil division signalsobtained from the third or fourth structure, the pupil division signalscorresponding to the color filter of the second color by a secondcoefficient, multiplying, among the pupil division signals obtained fromthe third or fourth structure, the pupil division signals correspondingto the color filter of the third color by a third coefficient,multiplying the pupil division signals obtained from the fifth and sixthstructures by a fourth coefficient, and adding products; and performingthe phase difference focus detection based on the luminance signals,wherein, upon generating the luminance signals, the luminance signalscorresponding to light fluxes passing through pupil regions divided infirst direction are generated by using the pupil division signalsobtained from the first structures and setting the fourth coefficientsmaller than the first coefficient and larger than the second and thirdcoefficients, the luminance signals corresponding to light fluxespassing through pupil regions divided in second direction are generatedby using the pupil division signals obtained from the second structuresand setting the fourth coefficient smaller than the first coefficientand larger than the second and third coefficients, the luminance signalscorresponding to light fluxes passing through pupil regions divided inthird direction are generated by using the pupil division signalsobtained from the first structures and setting the fourth coefficientlarger than the first coefficient and the first coefficient smaller thanthe second and third coefficients, the luminance signals correspondingto light fluxes passing through pupil regions divided in fourthdirection are generated by using the pupil division signals obtainedfrom the second structures and setting the fourth coefficient largerthan the first coefficient and the first coefficient smaller than thesecond and third coefficients, wherein the focus detection is performedfor each of the first to fourth directions, and wherein the first tofourth directions are different from each other.

Further, according to the present invention, provided is anon-transitory computer-readable storage medium, the storage mediumstoring a program that is executable by the computer, wherein theprogram includes program code for causing the computer to function as amethod of performing phase difference focus detection by obtaining andusing pupil division signals corresponding to light fluxes passingthrough different pupil regions from signals output from an image sensorthat comprises a plurality of microlenses and a pixel region including,with respect to each of the plurality of microlenses, a plurality offirst sensitivity regions formed at first depth from a light incidentsurface, a plurality of second sensitivity regions formed at seconddepth which is deeper than the first depth, and a plurality ofconnection portions that electrically connect the plurality of firstregions and the plurality of second regions in different combinations,wherein, at least for a part of the plurality of microlenses, theplurality of first regions and the plurality of second regions areconnected by the plurality of connection portions to form either a firststructure or a second structure, the first structure and the secondstructure dividing a pupil region in directions orthogonal to each otherand being covered with color filters of a first color, and at least foranother part of the plurality of microlenses, the plurality of firstregions and the plurality of second regions are connected by theplurality of connection portions to form either a third structure or afourth structure, the third structure and the fourth structure dividingthe pupil region in directions orthogonal to each other and in differentdirections from the first structure and the second structure and beingcovered with color filters of either a second color or a third color,and the first to fourth structures being arranged so that the colorfilters are in Bayer arrangement, the method comprising: generatingluminance signals by multiplying the pupil division signals obtainedfrom the first or second structure by a first coefficient, multiplying,among the pupil division signals obtained from the third or fourthstructure, the pupil division signals corresponding to the color filterof the second color by a second coefficient, multiplying, among thepupil division signals obtained from the third or fourth structure, thepupil division signals corresponding to the color filter of the thirdcolor by a third coefficient, and adding products; and performing thephase difference focus detection based on the luminance signals,wherein, upon generating the luminance signals, the luminance signalscorresponding to light fluxes passing through pupil regions divided infirst direction are generated by using the pupil division signalsobtained from the first structures and setting the first coefficientlarger than the second and third coefficients, the luminance signalscorresponding to light fluxes passing through pupil regions divided insecond direction are generated by using the pupil division signalsobtained from the second structures and setting the first coefficientlarger than the second and third coefficients, the luminance signalscorresponding to light fluxes passing through pupil regions divided inthird direction are generated by using the pupil division signalsobtained from the first structures and setting the first coefficientsmaller than the second and third coefficients, the luminance signalscorresponding to light fluxes passing through pupil regions divided infourth direction are generated by using the pupil division signalsobtained from the second structures and setting the first coefficientsmaller than the second and third coefficients, wherein the focusdetection is performed for each of the first to fourth directions, andwherein the first to fourth directions are different from each other.

Further, according to the present invention, provided is anon-transitory computer-readable storage medium, the storage mediumstoring a program that is executable by the computer, wherein theprogram includes program code for causing the computer to function as amethod of performing phase difference focus detection by obtaining andusing pupil division signals corresponding to light fluxes passingthrough different pupil regions from signals output from an image sensorthat comprises a plurality of microlenses and a pixel region including,with respect to each of the plurality of microlenses, a plurality offirst sensitivity regions formed at first depth from a light incidentsurface, a plurality of second sensitivity regions formed at seconddepth which is deeper than the first depth, and a plurality ofconnection portions that electrically connect the plurality of firstregions and the plurality of second regions in different combinations,wherein, at least for a part of the plurality of microlenses, theplurality of first regions and the plurality of second regions areconnected by the plurality of connection portions to form either a firststructure or a second structure, the first structure and the secondstructure dividing a pupil region in directions orthogonal to each otherand being covered with color filters of a first color, at least foranother part of the plurality of microlenses, the plurality of firstregions and the plurality of second regions are connected by theplurality of connection portions to form either a third structure or afourth structure, the third structure and the fourth structure dividingthe pupil region in directions orthogonal to each other and in differentdirections from the first structure and the second structure and beingcovered with color filters of either a second color or a third color,and at least for another part of the plurality of microlenses, theplurality of first regions and the plurality of second regions areconnected by the plurality of connection portions to form either fifthstructure or a sixth structure, the fifth structure being the same asthe first structure except for not being covered with a color filter,and the sixth structure being the same as the second structure exceptfor not being covered with a color filter, the method comprising:generating the luminance signals by multiplying the pupil divisionsignals obtained from the first or second structure by a firstcoefficient, multiplying, among the pupil division signals obtained fromthe third or fourth structure, the pupil division signals correspondingto the color filter of the second color by a second coefficient,multiplying, among the pupil division signals obtained from the third orfourth structure, the pupil division signals corresponding to the colorfilter of the third color by a third coefficient, multiplying the pupildivision signals obtained from the fifth and sixth structures by afourth coefficient, and adding products; and performing the phasedifference focus detection based on the luminance signals, wherein, upongenerating the luminance signals, the luminance signals corresponding tolight fluxes passing through pupil regions divided in first directionare generated by using the pupil division signals obtained from thefirst structures and setting the fourth coefficient smaller than thefirst coefficient and larger than the second and third coefficients, theluminance signals corresponding to light fluxes passing through pupilregions divided in second direction are generated by using the pupildivision signals obtained from the second structures and setting thefourth coefficient smaller than the first coefficient and larger thanthe second and third coefficients, the luminance signals correspondingto light fluxes passing through pupil regions divided in third directionare generated by using the pupil division signals obtained from thefirst structures and setting the fourth coefficient larger than thefirst coefficient and the first coefficient smaller than the second andthird coefficients, the luminance signals corresponding to light fluxespassing through pupil regions divided in fourth direction are generatedby using the pupil division signals obtained from the second structuresand setting the fourth coefficient larger than the first coefficient andthe first coefficient smaller than the second and third coefficients,wherein the focus detection is performed for each of the first to fourthdirections, and wherein the first to fourth directions are differentfrom each other.

Further features of the present invention will become apparent from thefollowing description of exemplary embodiments (with reference to theattached drawings).

BRIEF DESCRIPTION OF THE DRAWINGS

The accompanying drawings, which are incorporated in and constitute apart of the specification, illustrate embodiments of the invention, andtogether with the description, serve to explain the principles of theinvention.

FIG. 1 is a block diagram showing a schematic configuration of an imagecapturing apparatus according to an embodiment of the present invention.

FIG. 2 is an equivalent circuit diagram of a pixel according to theembodiment.

FIGS. 3A to 3F are plan views and cross-sectional views showingconfigurations of first and second pixels according to the embodiment.

FIGS. 4A to 4F are plan views and cross-sectional views showingconfigurations of third and fourth pixels according to the embodiment.

FIG. 5 is a schematic view showing a color filter arrangement in a pixelregion and division directions of pupil division signals according to afirst embodiment.

FIG. 6 is a schematic view showing a color filter arrangement in a pixelregion and division directions of pupil division signals according to asecond embodiment.

DESCRIPTION OF THE EMBODIMENTS

Hereinafter, embodiments will be described in detail with reference tothe attached drawings. Note, the following embodiments are not intendedto limit the scope of the claimed invention, and limitation is not madean invention that requires a combination of all features described inthe embodiments. Two or more of the multiple features described in theembodiments may be combined as appropriate. Furthermore, the samereference numerals are given to the same or similar configurations, andredundant description thereof is omitted.

FIG. 1 is a block diagram showing a schematic configuration of an imagecapturing apparatus according to an embodiment of the present invention.The image capturing apparatus of the present embodiment includes animage sensor 1, an overall control/arithmetic unit 2, an instructionunit 3, a timing generation unit 4, an imaging lens unit 5, a lens driveunit 6, a signal processing unit 7, a display unit 8 and a recordingunit 9.

The imaging lens unit 5 forms an optical image of a subject on the imagesensor 1. Although it is represented by one lens in the figure, theimaging lens unit 5 may include a plurality of lenses including a focuslens, a zoom lens, and a diaphragm, and may be detachable from the mainbody of the image capturing apparatus or may be integrally configuredwith the main body.

The image sensor 1 includes a pixel portion in which a plurality ofpixels each having a plurality of photoelectric conversion portions aretwo-dimensionally arranged, and converts the light incident through theimaging lens unit 5 into an electric signal and outputs it. The detailedconfiguration of the image sensor 1 will be described later, butbriefly, signals are read out from each pixel so that pupil divisionsignals, corresponding to light fluxes passed through different pupilregions of the imaging lens unit 5, that can be used in phase differencefocus detection and an image signal that is a signal of each pixel canbe acquired.

The signal processing unit 7 performs predetermined signal processingsuch as correction processing on the signals output from the imagesensor 1, and outputs the pupil division signals used for focusdetection and the image signal used for recording.

The overall control/arithmetic unit 2 comprehensively drives andcontrols the entire image capturing apparatus. In addition, the overallcontrol/arithmetic unit 2 also performs calculations for focus detectionusing the pupil division signals processed by signal processing unit 7,performs arithmetic processing for exposure control, predeterminedsignal processing, such as development for generating images forrecording/playback and compression, on the image signal.

The lens drive unit 6 drives the imaging lens unit 5, and performs focuscontrol, zoom control, aperture control, and the like on the imaginglens unit 5 according to control signals from the overallcontrol/arithmetic unit 2.

The instruction unit 3 accepts inputs such as shooting executioninstructions, drive mode settings for the image capturing apparatus, andother various settings and selections that are input from the outside bythe operation of the user, for example, and sends them to the overallcontrol/arithmetic unit 2.

The timing generation unit 4 generates a timing signal for driving theimage sensor 1 and the signal processing unit 7 according to a controlsignal from the overall control/arithmetic unit 2.

The display unit 8 displays information such as a preview image, aplayback image, and the drive mode settings of the image capturingapparatus.

The recording unit 9 is provided with a recording medium (not shown),and an image signal for recording is recorded. Examples of the recordingmedium include semiconductor memories such as flash memory. Therecording medium may be detachable from the recording unit 9 or may bebuilt-in.

Next, the pixel configuration in this embodiment will be described withreference to FIGS. 2 to 4 .

FIG. 2 is an equivalent circuit diagram of a pixel in the image sensor 1of the present embodiment. Each pixel in this embodiment has one of thestructures of first to fourth pixels P1 to P4 as described later withreference to FIGS. 3A to 3F and FIGS. 4A to 4F, however, the circuitconfiguration shown in FIG. 2 is common to the first to fourth pixels P1to P4.

Each pixel has photodiodes PD1 and PD2 that photoelectrically convertincident light, transfer transistors M1A and M1B, a reset transistor M2,a floating diffusion portion FD as a charge holding unit, anamplification transistor M3, and a selection transistor M4. As eachtransistor, an N-channel MOS transistor can be used. Hereinafter, itwill be described assuming that N-channel MOS transistors are used.

A control signal PTX1 is input to the gate of the transfer transistorM1A from a control circuit (not shown) in response to a timing signalfrom the timing generation unit 4. The transfer transistor M1A is turnedon while the control signal PTX1 is High (hereinafter referred to as“H”), and transfers the electric charge accumulated in the photodiodePD1 to the floating diffusion portion FD. Further, a control signal PTX2is input to the gate of the transfer transistor M1B from the controlcircuit (not shown), the transfer transistor M1B is turned on while thecontrol signal PTX2 is H and transfers the electric charge accumulatedin the photodiode PD2 to the floating diffusion portion FD.

A control signal PRES is input to the gate of the reset transistor M2from the control circuit (not shown), and the reset transistor M2 isturned ON while the control signal PRES is H, and the electric charge inthe floating diffusion portion FD is reset to a power supply voltageVDD. By setting the control signal PRES and the control signals PTX1 andPTX2 to H simultaneously, it is possible to reset the photodiodes PD1and PD2 to the power supply voltage VDD.

A control signal PSEL is input to the gate of the selection transistorM4 from the control circuit (not shown). When the selection transistorM4 is turned ON while the control signal PSEL is H, a signal voltageconverted from the amount of electric charge held in the floatingdiffusion portion FD by the amplification transistor M3 is output to thesignal line VL.

In the pixel of the present embodiment having the above circuitconfiguration, by turning on the transfer transistor M1A independently,the electric charge of the photodiode PD1 can be transferred to thefloating diffusion portion FD and read out. Hereinafter, the signal readout from the photodiode PD1 is referred to as an A signal. Further, byturning on the transfer transistor M1B independently, the electriccharge of the photodiode PD2 can be transferred to the floatingdiffusion portion FD and read out. Hereinafter, the signal read out fromthe photodiode PD2 is referred to as a B signal. The A signal and the Bsignal are pupil division signals, and an image signal (A+B signal) canbe obtained by adding the A signal and the B signal for each pixel inthe signal processing unit 7.

Alternatively, after reading out the A signal, the transfer transistorsM1A and M1B may be turned on at the same time to transfer the charges ofthe photodiodes PD1 and PD2 to the floating diffusion portion FD and thetransferred charge may be read out, whereby the A+B signal can beobtained. This A+B signal is an image signal, and by subtracting the Asignal from the A+B signal in the signal processing unit 7 to obtain theB signal, pupil division signals that can be used for focus detectioncan be obtained.

FIGS. 3A to 3F and FIGS. 4A to 4F are plan views and cross-sectionalviews showing schematic configurations of pixels having the circuitconfiguration shown in FIG. 2 in the present embodiment. In the presentembodiment, pixels having four different structures are used, and amongthe four types of pixels, FIGS. 3A to 3C show the structure of the firstpixel P1, FIGS. 3D to 3F show the structure of the second pixel P2,FIGS. 4A to 4C shows the structure of the third pixel P3, and FIGS. 4Dto 4F show the structure of the fourth pixel P4.

FIG. 3A is the schematic plan view of the first pixel P1. In FIG. 3A, amicrolens ML guides incident light to the photodiodes PD1 and PD2.Sensitivity regions 101, 102, 103, and 104 are of the photodiodes PD1and PD2.

The pupil of the imaging lens unit 5 and the sensitivity regions 101,102, 103, 104 have a conjugate relationship with respect to themicrolens ML, and the sensitivity regions 101, 102, 103, 104respectively receive light that has passed through different regions ofthe pupil of the imaging lens unit 5. Further, the sensitivity regions101 and 102, and the sensitivity regions 103 and 104 are arranged so asto have an optically conjugate relationship with respect to themicrolens ML. Further, the sensitivity regions 101 and 102 are arrangedso as to divide the pupil of the imaging lens unit 5 in the verticaldirection in the drawing, and the sensitivity regions 103 and 104 arearranged so as to divide the pupil of the imaging lens unit 5 in thehorizontal direction, which is different from the division direction ofthe sensitivity regions 101 and 102 by 90°.

A connecting portion 105 electrically connects the sensitivity regions101 and 103, and a connecting portion 106 electrically connects thesensitivity regions 102 and 104. In the first pixel P1, the sensitivityregions 101 and 103 and the connection portion 105 form the sensitivityregion of the photodiode PD1, and the sensitivity regions 102 and 104and the connecting portion 106 form the sensitivity region of thephotodiode PD2.

Reference numeral 107 denotes a gate electrode of the transfertransistor M1A, and reference numeral 108 denotes a gate electrode ofthe transfer transistor M1B. Reference numeral 109 denotes asemiconductor region constituting the floating diffusion portion FD.

A schematic view of the X1-X2 cross section of the first pixel P1 shownin FIG. 3A is shown in FIG. 3B, and a schematic view of the X3-X4 crosssection is shown in FIG. 3C. In FIG. 3B and FIG. 3C, it is assumed thatlight is incident from the lower side of the drawing (microlens MLside), and the depth in the following description indicates the depthfrom the incident surface toward the upper side of the drawing.Sensitivity regions 101 and 102 are provided at the first depth in asemiconductor substrate 110. Further, sensitivity regions 103 and 104are provided at a second depth in the semiconductor substrate 110, whichis deeper than the first depth. The connecting portion 105 is providedbetween the sensitivity regions 101 and 103, and electrically connectsthe sensitivity regions 101 and 103. Further, the connecting portion 106is provided between the sensitivity regions 102 and 104, andelectrically connects the sensitivity regions 102 and 104.

A color filter 111 is configured between the microlens ML and thesemiconductor substrate 110. In the present embodiment, the first pixelP1 is provided with an R filter, as the color filter 111, that transmitsred light.

FIG. 3D is a schematic plan view of the second pixel P2. Further, aschematic view of the X1-X2 cross section of the second pixel P2 shownin FIG. 3D is shown in FIG. 3E, and a schematic view of the X3-X4 crosssection is shown in FIG. 3F. Similar to FIGS. 3B and 3C, in FIGS. 3E and3F, it is assumed that light is incident from the lower side of thedrawing (microlens ML side), and the depth in the following descriptionindicates the depth from the incident surface toward the upper side ofthe drawing.

The second pixel P2 has different connection portions 205 and 206 fromthe first pixel P1, but other configurations and arrangements are thesame as those of the first pixel P1.

In the second pixel P2, the connecting portion 205 electrically connectsthe sensitivity regions 102 and 103, and the connecting portion 206electrically connects the sensitivity regions 101 and 104. Therefore, inthe second pixel P2, the sensitivity regions 102 and 103 and theconnection portion 205 form the sensitivity region of the photodiodePD1, and the sensitivity regions 101 and 104 and the connection portion206 form the sensitivity region of the photodiode PD2.

Further, in the present embodiment, the second pixel P2 is provided withan R filter, as the color filter 111, that transmits red light,similarly to the first pixel P1.

Here, the relationship between the depths at which the sensitivityregions 101, 102, 103, and 104 are formed in the first pixel P1 and thesecond pixel P2 and the wavelength of light that will bephotoelectrically converted in each sensitivity region will bedescribed.

In silicon, which is widely used in an image sensor for visible light,incident light is absorbed at the depth closer to the surface of siliconas the wavelength is shorter, and penetrates deeper as the wavelength islonger. For example, the depth at which half of the incident light isabsorbed is about 3.2 μm at a wavelength of 700 nm contained in redlight, about 0.8 μm at a wavelength of 530 nm contained in green light,and about 0.3 μm at a wavelength of 450 nm contained in blue light.

When the red light transmitted through the R filter 111 is incident onthe silicon substrate, a part of the red light is absorbed in thesensitivity regions 101 and 102 at the first depth and isphotoelectrically converted. Further, another part is absorbed andphotoelectrically converted in the sensitivity regions 103 and 104 atthe second depth, whose division direction is 90° different from that ofthe sensitivity regions 101 and 102.

In the first pixel P1, the electric charges generated in the sensitivityregions 101 and 103 are combined, and the electric charges generated inthe sensitivity regions 102 and 104 are combined. Therefore, thedivision direction of the pupil division signals obtained from the firstpixel P1 is a first direction D1 inclined both from the divisiondirection of the sensitivity regions 101 and 102, and the divisiondirection of the sensitivity regions 103 and 104. In this way, in thefirst pixel P1, the pupil division signals which are pupil-divided in adirection different from the division directions of the sensitivityregions 101 and 102 and the sensitivity regions 103 and 104 areacquired.

Further, in the second pixel P2, the electric charges generated in thesensitivity regions 102 and 103 are combined, and the electric chargesgenerated in the sensitivity regions 101 and 104 are combined.Therefore, the division direction of the pupil division signals obtainedfrom the second pixel P2 is a second direction D2 orthogonal to thefirst direction D1. In this way, also in the second pixel P2, similarlyto the first pixel P1, the pupil division signals which arepupil-divided in a direction different from the division directions ofthe sensitivity regions 101 and 102 and of the sensitivity regions 103and 104 are acquired.

Next, the configurations of the third pixel P3 and the fourth pixel P4will be described.

FIG. 4A is a schematic plan view of the third pixel P3. Further, aschematic view of the X1-X2 cross section of the third pixel P3 shown inFIG. 4A is shown in FIG. 4B, and a schematic view of the X3-X4 crosssection is shown in FIG. 4C. Similar to FIGS. 3B and 3C, in FIGS. 4B and4C, it is assumed that light is incident from the lower side of thedrawing (microlens ML side), and the depth in the following descriptionindicates the depth from the incident surface toward the upper side ofthe drawing.

The third pixel P3 shown in FIGS. 4A to 4C has a different color filter311 from the first pixel P1, but the other configuration and arrangementare the same as the first pixel P1, and thus the description thereofwill be omitted. As the color filter 311 of the third pixel P3, a Gfilter that transmits green light or a B filter that transmits bluelight is provided.

FIG. 4D is a schematic plan view of the fourth pixel P4. Further, aschematic view of the X1-X2 cross section of the fourth pixel P4 shownin FIG. 4D is shown in FIG. 4E, and a schematic view of the X3-X4 crosssection is shown in FIG. 4F. Similar to FIGS. 3B and 3C, in FIGS. 4E and4F, it is assumed that light is incident from the lower side of thedrawing (microlens ML side), and the depth in the following descriptionindicates the depth from the incident surface toward the upper side ofthe drawing.

In the fourth pixel P4, sensitivity regions 401 and 402 are provided atthe first depth of the semiconductor substrate 110, and the sensitivityregions 401 and 402 are arranged such that the pupil of the imaging lensunit 5 is divided in the division direction 900 different from thedivision direction of the sensitivity regions 101 and 102 of the thirdpixel P3, namely, in the horizontal direction of the drawing. Thearrangement of the microlens ML, the sensitivity regions 103 and 104,the gate electrodes 107 and 108 of the transfer transistors, and thefloating diffusion portion 109 is the same as that of the third pixelP3.

In the fourth pixel P4, the connecting portion 105 electrically connectsthe sensitivity regions 401 and 103, and the connecting portion 106electrically connects the sensitivity regions 402 and 104. Therefore, inthe fourth pixel P4, the sensitivity regions 401 and 103 and theconnection portion 105 form the sensitivity region of the photodiodePD1, and the sensitivity regions 402 and 104 and the connection portion106 form the sensitivity region of the photodiode PD2.

With this connection configuration, even if the arrangement of thesensitivity regions at the first depth is different between the thirdpixel P3 and the fourth pixel P4, the arrangement of the sensitivityregions at the second depth is the same in the third pixel P3 and thefourth pixel P4. Accordingly, the electric charge transfercharacteristics of the third pixel P3 and the fourth pixel P4 can bemade uniform.

Further, the fourth pixel P4 is provided with a G filter that transmitsgreen light or B filter that transmits blue light, as the color filter311, similarly to the third pixel P3.

Next, the relationship between the depths at which the sensitivityregions 101, 102, 103, 104, 401 and 402 are formed in the first pixel P1and the second pixel P2 and the wavelength of light that will bephotoelectrically converted in each sensitivity region will bedescribed.

Unlike red light, most of the green light and blue light transmittedthrough the G filter or B filter are absorbed in the sensitivity regionsof the first depth and photoelectrically converted. Therefore, the pupildivision signals which are pupil-divided in the substantially samedirection as that of the sensitivity regions of the first depth areobtained. Therefore, the division direction of pupil division signalsobtained from the third pixel P3 is a third direction D3, which isdifferent from the first direction D1 and the second direction D2.Further, the division direction of the pupil division signals obtainedfrom the fourth pixel P4 is a fourth direction D4 orthogonal to thethird direction D3.

First Embodiment

Next, the first embodiment of the present invention will be described.FIG. 5 is a schematic top view of the image sensor 1 according to thefirst embodiment, and shows an example in which a plurality of first tofourth pixels P1 to P4 having the above configuration are arranged in amatrix.

In FIG. 5 , arrows indicate the division directions of the pupildivision signals output from the first to fourth pixels P1 to P4 shownin FIGS. 3A to 3F and FIGS. 4A to 4F. That is, arrows rising to the leftrepresent the first direction D1, arrows rising to the right representsthe second direction D2, arrows in the vertical direction represents thethird direction D3, and arrows in the horizontal direction representsthe fourth direction D4. Further, the first pixels P1 and the secondpixels P2 having the R filter and the third pixels P3 and the fourthpixels P4 having the G filter or the B filter are arranged so that thearrangement of the color filters is a Bayer arrangement.

By providing the first to fourth pixels P1 to P4 in a pixel region 10,it is possible to acquire pupil division signals in which the pupils aredivided in the first to fourth directions D1 to D4.

The overall control/arithmetic unit 2 performs arithmetic processing forfocus detection on the pupil division signals obtained from the imagesensor 1 and obtains a defocus amount. Since a known method can be usedas a method for obtaining the defocus amount from the pupil divisionsignals, it will be briefly described below.

From the first photodiode PD1 and the second photodiode PD2 of eachfirst pixel P1 arranged in the pixel region 10, pupil division signalsR1A and R1B corresponding to light fluxes that have passed through pupilregions divided in the first direction D1 of the imaging lens unit 5 areoutput, respectively. The defocus amount in the first direction D1 canbe obtained by performing the correlation calculation while relativelyshifting an A image composed by collecting the pupil division signalsR1A and a B image composed by collecting the pupil division signals R1B.At this time, information on the reliability of the obtained defocusamount is also acquired.

Further, from the first photodiode PD1 and the second photodiode PD2 ofeach second pixel P2 arranged in the pixel region 10, pupil divisionsignals R2A and R2B corresponding to light fluxes that have passedthrough pupil regions divided in the second direction D2 of the imaginglens unit 5 are output, respectively. The defocus amount in the seconddirection D2 can be obtained by performing the same correlationcalculation using an A image composed by collecting the pupil divisionsignals R2A and a B image composed by collecting the pupil divisionsignals R2B. At this time, information on the reliability of theobtained defocus amount is also acquired.

Furthermore, among the third pixels P3 arranged in the pixel region 10,from the first photodiode PD1 and the second photodiode PD2 of eachthird pixel P3 covered with the G filter, a pair of pupil divisionsignals G3A and G3B corresponding to light fluxes that have passedthrough pupil regions divided in the third direction D3 of the imaginglens unit 5 are output, respectively. The defocus amount in the thirddirection D3 can be obtained by performing the same correlationcalculation using an A image composed by collecting the pupil divisionsignals G3A and a B image composed by collecting the pupil divisionsignals G3B. At this time, information on the reliability of theobtained defocus amount is also acquired.

Further, among the third pixels P3 arranged in the pixel region 10, fromthe first photodiode PD1 and the second photodiode PD2 of each thirdpixel P3 covered with the B filter, a pair of pupil division signals B3Aand B3B corresponding to light fluxes that have passed through pupilregions divided in the third direction D3 of the imaging lens unit 5 areoutput, respectively. The defocus amount in the third direction D3 canbe obtained by performing the same correlation calculation using an Aimage composed by collecting the pupil division signals B3A and a Bimage composed by collecting the pupil division signals B3B. At thistime, information on the reliability of the obtained defocus amount isalso acquired.

Further, among the fourth pixels P4 arranged in the pixel region 10,from the first photodiode PD1 and the second photodiode PD2 of eachfourth pixel P4 covered with the G filter, a pair of pupil divisionsignals G4A and G4B corresponding to light fluxes that have passedthrough pupil regions divided in the fourth direction D4 of the imaginglens unit 5 are output, respectively. The defocus amount in the fourthdirection D4 can be obtained by performing the same correlationcalculation using an A image composed by collecting the pupil divisionsignals G4A and a B image composed by collecting the pupil divisionsignals G4B. At this time, information on the reliability of theobtained defocus amount is also acquired.

Further, among the fourth pixels P4 arranged in the pixel region 10,from the first photodiode PD1 and the second photodiode PD2 of eachfourth pixel P4 covered with the B filter, a pair of pupil divisionsignals B4A and B4B corresponding to light fluxes that have passedthrough pupil regions divided in the first direction D4 of the imaginglens unit 5 are output, respectively. The defocus amount in the fourthdirection D4 can be obtained by performing the same correlationcalculation using an A image composed by collecting the pupil divisionsignals B4A and a B image composed by collecting the pupil divisionsignals B4B. At this time, information on the reliability of theobtained defocus amount is also acquired.

Then, the overall control/arithmetic unit 2 obtains a driving amount ofthe focus lens based on the obtained six defocus amounts and theinformation on the reliability. Then, the lens drive unit 6 iscontrolled based on the obtained driving amount, and the lens drive unit6 drives the imaging lens unit 5, thereby performing focus control.

The defocus amounts in the third direction D3 and the fourth directionD4 may be obtained for either the G filter or the B filter.

As described above, according to the first embodiment, it is possible toimprove the accuracy of focus detection in the increased number ofdirections in which the brightness of subject changes.

<Modification>

When calculating the defocus amount, luminance signals may be generatedfrom the pupil division signals obtained from the first to fourth pixelsP1 to P4, and the generated luminance signals may be used forcorrelation calculation in the first to fourth directions D1 to D4. Bydoing so, it is possible to reduce the number of correlationcalculations as compared with performing the correlation calculation intwo directions for each of the R, G, and B signals as described above.

A conversion method for generating a luminance signal from the pupildivision signals of the first to fourth pixels P1 to P4 will bedescribed below. The following equations (1) to (4) are used for thegeneration of the luminance signals, and each conversion is performed byusing the signals obtained from the first photodiodes PD1 of each of thefirst to fourth pixels P1 to P4 or the signals obtained from the secondphotodiodes PD2 of each of the first to fourth pixels P1 to P4. That is,in the equations (1) to (4), R1 corresponds to the pupil division signalR1A or R1B, and R2 corresponds to the pupil division signal R2A or R2B.Further, G3 corresponds to the pupil division signal G3A or G3B, G4corresponds to the pupil division signal G4A or G4B, B3 corresponds tothe pupil division signal B3A or B3B, and B4 corresponds to the pupildivision signals B4A or B4B. (x, y) indicates the coordinates of thedesired luminance signal.

Y1(x,y)=α1×R1(x,y)+β1×G3(x,y)+γ1×B3(x,y)  (1)

Y2(x,y)=α1×R2(x,y)+β1×G4(x,y)+γ1×B4(x,y)  (2)

Y3(x,y)=α2×R1(x,y)+β2×G3(x,y)+γ2×B3(x,y)  (3)

Y4(x,y)=α2×R2(x,y)+β2×G4(x,y)+γ2×B4(x,y)  (4)

Equation (1) is for obtaining a luminance signal Y1(x, y) to be used asthe pupil division signals corresponding to light fluxes that havepassed through pupil regions divided in the first direction D1 of theimaging lens unit 5 at the coordinates (x, y). R1(x, y) is multiplied bya coefficient α1, G3 (x, y) is multiplied by a coefficient β1, and B3(x, y) is multiplied by a coefficient γ1, and the products are added toobtain the luminance signal Y1(x, y) at the coordinates (x, y). Asdescribed above, for each of the pupil division signals output from thephotodiodes P1 and P2, the luminance signal Y1(x, y) is calculated, andthe luminance signals Y1(x, y) are collected to generate the A image andthe B image, respectively, and used for correlation calculation in thefirst direction D1. At this time, by setting the magnitude relationbetween the coefficients to α1>β1 and γ1, more weight is put on thepupil division signal R1 whose division direction of the pupil divisionsignals is close to the direction of the correlation calculation whenconverting to the luminance signal.

In the image sensor in which the color filters are Bayer-arranged,either of R, G, and B signals will be obtained at the coordinates (x,y). Therefore, for other colors, virtual signals at the coordinates (x,y) may be generated using a known interpolation calculation using pixelsignals of the other colors located near the coordinates (x, y).

Equation (2) is for obtaining a luminance signal Y2(x, y) to be used asthe pupil division signals corresponding to light fluxes that havepassed through pupil regions divided in the second direction D2,orthogonal to the first direction D1, of the imaging lens unit 5 at thecoordinates (x, y). In equation (2), the coefficients α1, β1, γ1 commonto equation (1) are used, and R2(x, y) is multiplied by the coefficientα1, G4 (x, y) is multiplied by the coefficient β1, and B4 (x, y) ismultiplied by the coefficient γ1, and the products are added to obtainthe luminance signal Y2(x, y) at the coordinates (x, y). As describedabove, for each of the pupil division signals output from thephotodiodes P1 and P2, the luminance signal Y2(x, y) is calculated, andthe luminance signals Y2(x, y) are collected to generate the A image andthe B image, respectively, and used for correlation calculation in thesecond direction D2.

Equation (3) is for obtaining a luminance signal Y3(x, y) to be used asthe pupil division signals corresponding to light fluxes that havepassed through pupil regions divided in the third direction D3, which isdifferent from the first direction D1 and the second direction D2, ofthe imaging lens unit 5 at the coordinates (x, y). In Equation (3),R1(x, y) is multiplied by a coefficient α2, G3 (x, y) is multiplied by acoefficient β2, and B3 (x, y) is multiplied by a coefficient γ2, and theproducts are added to obtain the luminance signal Y3(x, y) at thecoordinates (x, y). At this time, by setting the magnitude relationbetween the coefficients to β2 and γ2>α1, more weight is put on thesignal from the G pixel and B pixel whose division direction of thepupil division signals is close to the direction of the correlationcalculation when converting to the luminance signal. Then, as describedabove, for each of the pupil division signals output from thephotodiodes P1 and P2, the luminance signal Y3(x, y) is calculated, andthe luminance signals Y3(x, y) are collected to generate the A image andthe B image, respectively, and used for correlation calculation in thethird direction D3. The magnitude relation between the coefficients ofthe equations (1) and (3) is α1>α2, β1<β2, and γ1<γ2.

Equation (4) is for obtaining a luminance signal Y4(x, y) to be used asthe pupil division signals corresponding to light fluxes that havepassed through pupil regions divided in the fourth direction D4,orthogonal to the third direction D3, of the imaging lens unit 5 at thecoordinates (x, y). In equation (4), the coefficients α2, β2, γ2 commonto equation (3) are used, and R2(x, y) is multiplied by the coefficientα2, G4 (x, y) is multiplied by the coefficient β2, and B4 (x, y) ismultiplied by the coefficient γ2, and the products are added to obtainthe luminance signal Y4(x, y) at the coordinates (x, y). As describedabove, for each of the pupil division signals output from thephotodiodes P1 and P2, the luminance signal Y4(x, y) is calculated, andthe luminance signals Y4(x, y) are collected to generate the A image andthe B image, respectively, and used for correlation calculation in thefourth direction D4.

In this way, the number of correlation calculations can be reduced byperforming the correlation calculation after obtaining the pupildivision luminance signals at each coordinate.

Second Embodiment

Next, a second embodiment of the present invention will be described. Inthe second embodiment, the image sensor 1 is configured, in addition tothe plurality of first to fourth pixels P1 to P4 described withreference to FIGS. 2 to 4 , with fifth pixels P5 and sixth pixels P6having the same configuration of the first pixels P1 and the secondpixels P2 except for being covered by W filters that transmit whitelight instead of the color filters 111 or not covered by any filter.That is, the division direction of the pupil division signals outputfrom the fifth pixels P5 is equal to the division direction of the pupildivision signals output from the first pixels P1, and the divisiondirection of the pupil division signals output from the sixth pixels P6is equal to the division direction of the pupil division signals outputfrom the second pixels P2.

Therefore, from the fifth pixels P5, pupil division signals W1A and W1Bdivided in the first direction D1 which is different from the divisiondirection of the sensitivity region can be obtained. Further, from thesixth pixels P6, pupil division signals W2A and W2B divided in thesecond direction D2 which is orthogonal to the first direction D1 can beacquired.

Thus, according to the second embodiment, in addition to the defocusamount obtained by using the pupil division signals of each colorcomponent, the defocus amount can be obtained by using the pupildivision signals based on white light. By using the pupil divisionsignals based on white light in this way, it is possible to perform moreaccurate focus detection when the brightness of a subject is low.

<Modification>

When the image sensor 1 has the configuration as shown in FIG. 6 , whendetermining the defocus amount, luminance signals may be generated fromthe pupil division signals obtained from the first to sixth pixels P1 toP6, and correlation calculations in the first to fourth directions D1 toD4 may be performed using the generated luminance signals. By doing so,it is possible to reduce the number of correlation calculations ascompared with performing the correlation calculations in two directionsfor each of the R, G, B, and W signals as described above.

A conversion method for generating luminance signals from the pupildivision signals of the first to sixth pixels P1 to P6 will be describedbelow. The following equations (5) to (8) are equations showing aconversion method for generating luminance signals. Equations (5) to (8)are different from equations (1) to (4) in that the pupil divisionsignals from the fifth pixel P5 and the sixth pixel P6 are further used.In equations (5) to (8), W1 represents the pupil division signal W1A orW1B, and W2 represents the pupil division signal W2A or W2B.

Y1(x,y)=α1×R1(x,y)+β1×G3(x,y)+γ1×B3(x,y)+δ1×W1(x,y)   (5)

Y2(x,y)=α1×R2(x,y)+β1×G4(x,y)+γ1×B4(x,y)+δ1×W2(x,y)   (6)

Y3(x,y)=α2×R1(x,y)+β2×G3(x,y)+γ2×B3(x,y)+Ω×W1(x,y)   (7)

Y4(x,y)=α2×R2(x,y)+β2×G4(x,y)+γ2×B4(x,y)+δ2×W2(x,y)   (8)

Equation (5) is for obtaining a luminance signal Y1(x, y) to be used asthe pupil division signals divided in the first direction D1 at thecoordinates (x, y). The value obtained by multiplying W1 by acoefficient 81 and adding the product to the above-mentioned equation(1) is defined as the luminance signal Y1(x, y) at the coordinates (x,y). Then, for each of the pupil division signals output from thephotodiodes P1 and P2, the luminance signal Y1(x, y) is calculated, andthe luminance signals Y1(x, y) are collected to generate the A image andthe B image, respectively, and used for correlation calculation in thefirst direction D1.

Equation (6) is for obtaining a luminance signal Y2(x, y) to be used asthe pupil division signals divided in the second direction D2 at thecoordinates (x, y). The value obtained by multiplying W2 by thecoefficient 81 and adding the product to the above-mentioned equation(2) is defined as the luminance signal Y2(x, y) at the coordinates (x,y). Then, for each of the pupil division signals output from thephotodiodes P1 and P2, the luminance signal Y2(x, y) is calculated, andthe luminance signals Y2(x, y) are collected to generate the A image andthe B image, respectively, and used for correlation calculation in thesecond direction D2.

Equation (7) is for obtaining a luminance signal Y3(x, y) to be used asthe pupil division signals divided in the third direction D3 at thecoordinates (x, y). The value obtained by multiplying W1 by acoefficient 82 and adding the product to the above-mentioned equation(3) is defined as the luminance signal Y3(x, y) at the coordinates (x,y). Then, for each of the pupil division signals output from thephotodiodes P1 and P2, the luminance signal Y3(x, y) is calculated, andthe luminance signals Y4(x, y) are collected to generate the A image andthe B image, respectively, and used for correlation calculation in thethird direction D3.

Equation (8) is for obtaining a luminance signal Y4(x, y) to be used asthe pupil division signals divided in the fourth direction D4 at thecoordinates (x, y). The value obtained by multiplying W2 by thecoefficient 82 and adding the product to the above-mentioned equation(4) is defined as the luminance signal Y4(x, y) at the coordinates (x,y). Then, for each of the pupil division signals output from thephotodiodes P1 and P2, the luminance signal Y4(x, y) is calculated, andthe luminance signals Y4(x, y) are collected to generate the A image andthe B image, respectively, and used for correlation calculation in thefourth direction D4.

At this time, similarly to the first embodiment, more weight is put onthe signals whose division direction of the pupil division signals isclose to the direction of the correlation calculation when converting tothe luminance signal. Since the W filter transmits light in alltransmission wavelength bands of the R, G, and B filters, in thismodification, the magnitude relationship between the weightingcoefficients is determined as α1>δ1>β1 and γ1, α2<δ2<β2 and γ2, andδ1>δ2.

The magnitude relationship between the weighting coefficients by whichthe pupil division signals of other colors are multiplied is the same asthat of the modification of the first embodiment.

In this way, the number of correlation calculations can be reduced byperforming the correlation calculation after obtaining the pupildivision luminance signals at each coordinate.

Note that in the first and second embodiments described above, as shownin FIGS. 3A to 3F and FIGS. 4A to 4F, the case where each sensitivityregion is rectangular has been described, but the present invention isnot limited to this. If the shape of each sensitivity region is thesame, for example, it may be a triangle, and the same effect can beobtained.

OTHER EMBODIMENTS

The present invention may be applied to a system composed of a pluralityof devices or an apparatus composed of one device.

Embodiment(s) of the present invention can also be realized by acomputer of a system or apparatus that reads out and executes computerexecutable instructions (e.g., one or more programs) recorded on astorage medium (which may also be referred to more fully as a‘non-transitory computer-readable storage medium’) to perform thefunctions of one or more of the above-described embodiment(s) and/orthat includes one or more circuits (e.g., application specificintegrated circuit (ASIC)) for performing the functions of one or moreof the above-described embodiment(s), and by a method performed by thecomputer of the system or apparatus by, for example, reading out andexecuting the computer executable instructions from the storage mediumto perform the functions of one or more of the above-describedembodiment(s) and/or controlling the one or more circuits to perform thefunctions of one or more of the above-described embodiment(s). Thecomputer may comprise one or more processors (e.g., central processingunit (CPU), micro processing unit (MPU)) and may include a network ofseparate computers or separate processors to read out and execute thecomputer executable instructions. The computer executable instructionsmay be provided to the computer, for example, from a network or thestorage medium. The storage medium may include, for example, one or moreof a hard disk, a random-access memory (RAM), a read only memory (ROM),a storage of distributed computing systems, an optical disk (such as acompact disc (CD), digital versatile disc (DVD), or Blu-ray Disc (BD)™),a flash memory device, a memory card, and the like.

While the present invention has been described with reference toexemplary embodiments, it is to be understood that the invention is notlimited to the disclosed exemplary embodiments. The scope of thefollowing claims is to be accorded the broadest interpretation so as toencompass all such modifications and equivalent structures andfunctions.

This application claims the benefit of Japanese Patent Application No.2020-107231, filed on Jun. 22, 2020 which is hereby incorporated byreference herein in its entirety.

What is claimed is:
 1. An image sensor comprising: a plurality ofmicrolenses; and a pixel region including, with respect to each of theplurality of microlenses, a plurality of first sensitivity regionsformed at first depth from a light incident surface, a plurality ofsecond sensitivity regions formed at second depth which is deeper thanthe first depth, and a plurality of connection portions thatelectrically connect the plurality of first regions and the plurality ofsecond regions in different combinations.